At least 4,650 foreigners have been detained by the police in operation "Illegal Immigrant" in two districts of the Moscow region, Russian authorities announced Thursday.

On Wednesday alone, 1,800 migrants were swept up in a massive raid on the supplies and building materials markets in Odintsovo.

Another 2,850 illegal immigrants were detained over the past two months in the city of Lyubertsy.

Authorities in the capital region detained thousands of people over the past few months in an unprecedented campaign against illegal immigrants launched with one eye on September's municipal and regional elections.

News reports about the detention of thousands of foreigners in Moscow have been appearing each day for three weeks, after the beating dealt out to a police officer by a man from the Russian Caucasus republic of Dagestan served as a pretext for massive raids to crack down on illegal immigration.

Polls show 75 percent of Russians look critically on the immigrants and are in favor of harsher immigration laws.

Feelings against illegal immigrants, in particular those coming from former Soviet republics in Central Asia, are especially strong in Moscow, where - according to some estimates - up to 2.5 million foreigners live. EFE